//file : lock.c
            ＃i nclude <unistd.h>
            ＃i nclude <stdlib.h>
            ＃i nclude <stdio.h>
            ＃i nclude <fcntl.h>
            ＃i nclude <errno.h>
            int main()
            {
            int file_desc;
            int save_errno;
            file_desc = open("/tmp/LockFile.test", O_RDWR | O_CREAT | O_EXCL, 0444);
            if (file_desc < 0)
            {
            save_errno = errno;
            printf("Open failed with error is %d\n", save_errno);
            }
            else {
            printf("Open succeeded\n");
            }
            exit(EXIT_SUCCESS);
            }